Semiconductor constructions

ABSTRACT

The invention includes methods of forming isolation regions. An opening can be formed to extend into a semiconductor material, and an upper periphery of the opening can be protected with a liner while a lower periphery is unlined. The unlined portion can then be etched to form a widened region of the opening. Subsequently, the opening can be filled with insulative material to form an isolation region. Transistor devices can then be formed on opposing sides of the isolation region, and electrically isolated from one another with the isolation region. The invention also includes semiconductor constructions containing an electrically insulative isolation structure extending into a semiconductor material, with the structure having a bulbous bottom region and a stem region extending upwardly from the bottom region to a surface of the semiconductor material.

TECHNICAL FIELD

The invention pertains to semiconductor processing methods, and tosemiconductor constructions.

BACKGROUND OF THE INVENTION

As the level of integration of integrated circuitry increases, it isbecoming an ever greater challenge to maintain electrical isolationbetween adjacent electrical devices. For instance, the density ofdynamic random access memory (DRAM) has been approximately quadrupledevery three years by virtue of advances in DRAM technology. As thedevice dimensions scale down, it is becoming more and more challengingto maintain electrical isolation (especially cell-to-cell isolation) inthe memory array region due to reduction of space for isolationstructures. A common isolation structure is a trenched isolationstructure (such as, for example, a shallow trench isolation structure),and it is becoming increasingly challenging to form and fill thetrenches of such isolation structures within the ever-decreasing realestate available for the structures.

Cell-to-cell isolation is becoming a greater factor in causing failureof integrated circuitry, with such failure frequently being due toleakage around a trenched isolation region. Field implants have beenutilized in an attempt to prevent leakage around trenched isolationstructures, but such can create problems with refresh.

Cell-to-cell isolation is already problematically challenging, and isexpected to become even more challenging for future generations ofdevices due to the tighter pitch and smaller space available forisolation structures of the future. Accordingly, it is desirable todevelop new isolation structures. It would be particularly desirable forsuch isolation structures to be suitable for cell-to-cell isolation.

SUMMARY OF THE INVENTION

In one aspect, the invention includes a semiconductor processing method.A semiconductor material is provided, and an opening is formed to extendinto the semiconductor material. An upper periphery of the opening isprovided with a liner while at least a portion of a lower periphery ofthe opening is unlined. Etching is conducted through the unlined portionto form a bulbous extension of the opening, and such bulbous extensionis substantially filled with insulative material.

In one aspect, the invention encompasses a semiconductor processingmethod. A semiconductor material is provided and an opening is formed toextend into the semiconductor material to a first depth. A periphery ofthe opening is lined with a protective liner, except for the lowerregion of the opening. Etching is conducted through the unlined lowerregion of the opening with an etch that is at least substantiallyisotropic to form a widened extension of the opening.

In one aspect, the invention encompasses a semiconductor processingmethod. A silicon-containing material is provided. An opening is formedto extend into the silicon-containing material. The opening has abulbous bottom region and a stem region extending upwardly from thebottom region to a surface of the silicon-containing material. Theopening is substantially filled with insulative material. A firsttransistor device is formed on one side of the opening, with the firsttransistor device having a pair of first source/drain regions extendinginto the silicon-containing material. A second transistor device isformed on an opposing side of the opening from the first transistordevice, with the second transistor device having a pair of secondsource/drain regions extending into the silicon-containing material. Theinsulative material within the opening is utilized to provide electricalisolation between the first and second transistor devices.

In one aspect, the invention includes a semiconductor construction. Theconstruction comprises a semiconductor material and an electricallyinsulative structure extending into the semiconductor material. Theelectrically insulative structure has a bulbous bottom region and a stemextending upwardly from the bottom region to a surface of thesemiconductor material. The construction can further include a firsttransistor device on one side of the electrically insulative structureand a second transistor device on an opposing side of the electricallyinsulative structure, with the insulative material of the insulativestructure providing electrical isolation between the first and secondtransistor devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic, cross-sectional view of a semiconductor waferfragment at a preliminary processing stage of an exemplary aspect of thepresent invention.

FIG. 2 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 1.

FIG. 3 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 2.

FIG. 4 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 3.

FIG. 5 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 4.

FIG. 6 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 5.

FIG. 7 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 6.

FIG. 8 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 7.

FIG. 9 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 8.

FIG. 10 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 9.

FIG. 11 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 9 in accordance with an aspectalternative to that of FIG. 10.

FIG. 12 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 4 in accordance with an aspect of theinvention alternative to that of FIG. 5.

FIG. 13 is a view of the FIG. 1 wafer fragment shown at a processingstage subsequent to that of FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

The invention includes processes in which bottom regions of openings ortrenches are expanded. In particular aspects, the openings havingexpanded bottom regions are filled with insulative material to createtrenched isolation structures. Such isolation structures can provideimprovements relative to prior art isolation structures for cell-to-cellisolation in a memory array. Some specific applications of the inventionutilize isolation structures formed in accordance with the invention toimprove refresh and functionality of devices associated with a memoryarray relative to the refresh and functionality that would occur inprior art constructions. In some aspects of the invention, the expandedbowl (i.e., expanded bottom region) of an isolation region formed inaccordance with the invention is kept relatively far away from channelregions of access devices so that operating parameters of the devices(for example, channel length and drive current) are not adverselyimpacted by the utilization of the isolation region of the presentinvention.

A particular aspect of the invention is described with reference toFIGS. 1-10.

Referring to FIG. 1, a semiconductor construction 10 is illustrated at apreliminary processing stage. Construction 10 comprises a substrate 12.The substrate can comprise, consist essentially of, or consist ofmonocrystalline silicon lightly doped with suitable background dopant,and in particular aspects can comprise, consist essentially of, orconsist of monocrystalline silicon lightly background doped with p-typedopant. To aid in interpretation of the claims that follow, the terms“semiconductive substrate” and “semiconductor substrate” are defined tomean any construction comprising semiconductive material, including, butnot limited to, bulk semiconductive materials such as a semiconductivewafer (either alone or in assemblies comprising other materialsthereon), and semiconductive material layers (either alone or inassemblies comprising other materials). The term “substrate” refers toany supporting structure, including, but not limited to, thesemiconductive substrates described above.

Although silicon is one exemplary semiconductor material that can beincorporated into substrate 12, it is to be understood that thesubstrate can comprise other semiconductor materials, including, forexample, germanium.

A layer 14 comprising, consisting essentially of, or consisting ofsilicon dioxide is formed over substrate 12; and a layer 16 comprising,consisting essentially of, or consisting of silicon nitride is formedover layer 14. The layers 14 and 16 are together patterned to form ahard mask over substrate 12. The patterned hard mask has an opening 18extending therethrough to an upper surface of substrate 12. Layers 14and 16 can be patterned through any suitable processing, including, forexample, forming photolithographically patterned photoresist over layer16, transferring a pattern from the photoresist to the underlying layers14 and 16, and subsequently removing the photoresist.

Referring to FIG. 2, opening 18 is extended into semiconductor materialof substrate 12. The opening is extended with a suitable anisotropicetch, and can be extended to any suitable depth within the substrate.For instance, if opening 18 is ultimately to be used in forming atrenched isolation region, the opening can be extended to a depthapproximately equal to that conventionally utilized for trenchedisolation regions. The opening can have any suitable shape, and inparticular aspects can be a trench extending longitudinally into and outof the page relative to the cross-sectional view of FIG. 2.

The opening 18 has a maximum cross-sectional width 19 extendingtransversely across the opening at a widest portion of the openingwithin substrate 12. Such width can be any suitable width, and inparticular aspects will be a width of less than or equal to about 100nanometers.

Referring next to FIG. 3, a liner 20 is formed along a periphery ofopening 18. The shown liner extends only along semiconductor materialsubstrate 12, and not along masking materials 14 and 16. However, it isto be understood that the invention also encompasses some aspects (notshown) in which the liner extends along exposed surfaces of layers 14and 16, as well as along exposed surfaces of semiconductor materialsubstrate 12.

Liner 20 can comprise any material suitable for protecting surfaces ofsubstrate 12 during a subsequent etch (discussed below). For instance,liner 20 can comprise, consist essentially of, or consist of silicondioxide. In such aspects, the liner can be formed by depositing silicondioxide within the opening, and/or can be formed by thermal oxidation ofexposed surfaces of a silicon-containing substrate 12 within theopening. If substrate 12 comprises semiconductor materials other thansilicon, the oxide formed within the opening as liner 20 can be an oxideother than silicon dioxide. The oxidation utilized to form liner 20 can,for example, comprise oxidation with an O₂ plasma, either in situ or exsitu, and in some aspects chlorine can also be incorporated into theoxidation chemistry.

In some aspects of the invention, liner 20 can comprise, consistessentially of, or consist of a polymeric organic material (or, in otherwords, an organic polymer). For instance, the liner can comprise,consist essentially of, or consist of a combination of carbon, hydrogenand fluorine. In such aspects, the polymer can be formed from one ormore of CHF₃, CH₂F₂, CH₃F, CF₄, CH₄, C₂H₆, C₂H₄, NH₃, and HBr. If theliner comprises an organic polymer, such can be directly onsemiconductor material of substrate 12 (as shown), or can be over anintervening layer, such as, for example, a thin layer of native oxide.

The deposition conditions utilized for forming liner 20 can comprisemoderate to high pressure, and low bias voltage to uniformly deposit theliner within opening 18. If the liner comprises a polymeric organicmaterial, the liner can be deposited over exposed surfaces of layers 14and 16 in addition to being deposited along exposed surfaces ofsemiconductor material substrate 12 within opening 18.

Referring next to FIG. 4, liner 20 is subjected to an anisotropic etchwhich removes the liner from along a lower region of opening 18 whileleaving the liner along an upper region of the opening. The liner 20appears to be broken into two separate segments in the showncross-sectional view of FIG. 4. It is to be understood, however, thatopening 18 can have a continuous sidewall if viewed from above, and thatliner 20 can thus extend all the way around a lateral periphery of thesidewall at the processing stage of FIG. 4.

In some aspects, opening 18 can be considered to have an upper peripheryand a lower periphery, with the lower periphery including, but not beinglimited to, a bottom-most portion of the opening. The shown etch hasremoved the liner from over the bottom-most portion of the opening, andnot removed liner from regions above the bottom-most portion. Thedelineation between the upper periphery of the opening and the lowerperiphery of the opening can occur at any location within the opening,with the general understanding being that the liner remaining at theprocessing stage of FIG. 4 protects an entirety of the upper peripheryof the opening, and that at least a portion of the lower periphery ofthe opening is unlined. The unlined portion of the lower periphery canbe the bottom-most portion of the lower periphery, can be a regionproximate the bottom-most portion of the lower periphery, or can be somecombination of the bottom-most portion of the opening and a regionproximate the bottom-most portion of the opening.

The etch chemistry utilized to remove liner 20 from the lower peripheryof the opening can be any suitable etch chemistry. For instance, ifliner 20 comprises, consists essentially of, or consists of silicondioxide or an organic polymer, the etch can utilize one or more of CF₄,CHF₃, CH₂F₂, HBr, and Cl₂; and would typically be conducted at lowpressure and with a moderate to high bias. The bias can cause the etchto be highly anisotropic.

The construction of FIG. 4 can be considered to contain an opening 18extending into semiconductor material of substrate 12, with an upperperiphery of the opening protected by the liner 20 and at least aportion of a lower periphery of the opening being unlined.Alternatively, the unlined portion of the opening can be considered tobe an unlined lower region of the opening, and the lined portion of theopening can be considered to be a lined upper region of the opening.

Referring next to FIG. 5, the liner 20 is utilized to protect sidewallsof opening 18 while the unlined portion of opening 18 is exposed to anetch. The etch is typically isotropic, substantially isotropic, or atleast a transition etch between an anisotropic etch and an isotropicetch. The etch widens the lower portion of opening 18 to form a widenedextension 30 of the opening. In the shown aspect of the invention, thewidened extension 30 is a bulbous extension.

The etch utilized to form widened extension 30 can comprise any suitableetch chemistry, and in particular aspects will comprise substantiallyisotropic chemistry selective for semiconductor material of substrate 12(such semiconductor material can be silicon, for example) relative tothe silicon dioxide of layer 14, the silicon nitride of layer 16, andthe material of liner 20. The etch chemistry can, for example, be basedon NF₃ and/or SF₆, and can also include one or more of HBr, CHF₃, CH₂F₂and O₂ as moderating agents (with such moderating agents beingspecifically included to suppress lateral etching so that the bowl 30ends up being relatively circular in configuration rather than beingoverly-elongated in lateral directions). The etching can be accomplishedutilizing either wet etch or dry etch processes.

Although the etching utilized to form the widened regions of the openingcan be isotropic etching, it is to be understood that the etching wouldtypically be substantially isotropic, rather than absolutely isotropic.In other words, the etch will typically have some minor anisotropiccomponent either purposely or due to, for example, difficulties increating an absolutely isotropic etch; but will be mostly isotropic. Forpurposes of interpreting this disclosure and the claims that follow, thephrase “at least substantially isotropic” is to be understood tocomprise substantially isotropic conditions and absolutely isotropicconditions.

The cross-sectional configuration of FIG. 5 can be considered tocomprise an opening 18 having a configuration of a narrow stem region 34extending upwardly from a widened bottom region 30. The shown widenedregion 30 has relatively sharp corners 32 where the widened regionsjoins with the narrow region of the opening. The sharpness of thecorners 32 can be modified by coupling an anisotropic first etch with anisotropic second etch during formation of widened region 30, as will bediscussed in more detail with reference to FIGS. 12 and 13 below. It isto be understood that the opening 18 can be in the shape of a trenchextending longitudinally into and out of the page relative to the showncross-sectional view of FIG. 5.

Referring to FIG. 6, liner 20 (FIG. 5) is removed from within the stemregion 34 of opening 18. Such removal can be accomplished with anysuitable etch chemistry.

The opening 18 of FIG. 6 can have any suitable dimensions. In someaspects, the stem region can have a maximum cross-sectional width 19 ofless than about 100 nanometers, and in particular aspects will have amaximum cross-sectional width of from about 50 nanometers to about 100nanometers. The widened region 30 can have a maximum cross-sectionalwidth 36 that is at least 10 nanometers greater than the width 19, andin particular aspects can be from about 20 nanometers greater to about80 nanometers greater than the width 19 in the shown cross-sectionalview (in other words, can extend from about 10 nanometers to about 40nanometers laterally outward on either side of the originalmost-laterally-outward sidewall edges of opening 18 in the showncross-sectional view).

Referring to FIG. 7, opening 18 is filled with material 40. Inparticular aspects of the invention, opening 18 is ultimately utilizedto form an electrical isolation region extending within substrate 12,and accordingly material 40 can correspond to an electrically insulativematerial. In such aspects, material 40 can comprise any suitableelectrically insulative composition or combination of compositions, andcan, for example, comprise, consist essentially of, or consist ofsilicon dioxide. Although the material 40 is shown filling an entiretyof opening 18, it is to be understood that the invention encompassesother aspects (not shown) in which the material only fills a portion ofopening 18. For instance, material 40 can substantially fill the bulbousextension 30 without entirely filling the rest of the opening, or cansubstantially fill the bulbous region 30 and also substantially fill thestem region 34 extending upwardly from the bulbous region.

Although the shown aspect of the invention has the liner removed fromwithin the stem region, it is to be understood that the invention alsoencompasses aspects in which the liner remains within the stem region asopening 18 is filled with various materials. For instance, if the linercomprises silicon dioxide, and the stem region is ultimately going to befilled with silicon dioxide to form an isolation region, the silicondioxide of the liner can remain within the stem region. However, it canbe advantageous to clean the liner from within the stem region in orderto remove contaminating materials that may have accumulated on the linerduring the processing of forming the opening 30, regardless of whetheror not the liner otherwise comprises a composition suitable forincorporation into materials that are going to be utilized to fill theopening.

Referring next to FIG. 8, construction 10 is subjected to polishing(such as, for example, chemical-mechanical polishing) to form aplanarized upper surface 41 extending across layer 16 and across anupper surface of insulative material 40. The planarization can stop atabout an uppermost surface of layer 16, or in some aspects can extendinto layer 16.

Referring to FIG. 9, layers 14 and 16 (FIG. 8) are removed. Thestructure comprising insulative material 40 can, in some aspects, be anisolation structure, and can be considered to correspond to a trenchedisolation structure. Such isolation structure has, in the showncross-sectional view, the widened base 30 (which can also be referred toas a bulbous region or bowl region) and the stem 34 extending upwardlyfrom such base. Circuit devices can be provided on opposing sides of theisolation structure, and the structure can then be utilized to provideelectrical separation between the devices.

FIG. 10 illustrates an exemplary construction utilizing the isolationstructure of material 40 to provide electrical isolation between a firsttransistor device 50 and a second transistor device 60. The firsttransistor device is formed on one side of the isolation structure, andthe second transistor device is formed on an opposing side of theisolation structure. The first transistor device comprises a transistorgate 52 comprising a gate dielectric material 54, a conductive gatematerial 56, and an insulative cap 58. The gate dielectric can, forexample, comprise, consist essentially of, or consist of silicondioxide. The conductive gate material can comprise any suitableelectrically conductive composition or combination of compositions, andin particular aspects will comprise one or more of various metals, metalcompositions, and conductively-doped semiconductor material (such as,for example, conductively-doped silicon). Electrically insulative cap 58can comprise any suitable electrically insulative composition orcombination of compositions, and in particular aspects will comprise oneor both of silicon nitride and silicon dioxide.

A pair of source/drain regions 57 are proximate gate 52, and areelectrically coupled to one another through a channel region beneathgate 52 and controlled by gate 52. Source/drain regions 57 compriseconductively-doped diffusion regions extending into substrate 12, andcan comprise one or both of p-type dopant and n-type dopant. The shownsource/drain regions 57 comprise lightly-doped extensions 59 andheavily-doped regions 55, as will be recognized by persons of ordinaryskill in the art.

Transistor device 50 is shown to comprise sidewall spacers 53 beside thegate 52. Such sidewall spacers can comprise any suitable composition orcombination of compositions, and in particular aspects will comprise,consist essentially of, or consist of one or both of silicon nitride andsilicon dioxide.

Transistor device 60 comprises a gate 62 containing gate dielectric 64,conductive gate material 66, and an insulative cap 68. The gatedielectric 64, conductive gate material 66 and insulative cap 68 cancomprise the same compositions as discussed above for gate dielectric54, conductive gate material 56, and insulative cap 58. Transistordevice 60 also comprises source/drain diffusion regions 67 extendinginto substrate 12, and having lightly-doped extensions 69 andheavily-doped regions 65. In some aspects, source/drain regions 57 canbe referred to as first source/drain regions, and source/drain region 67can be referred to as second source/drain regions.

The second transistor device 60 comprises sidewall spacers 63 which areanalogous to the sidewall spacers 53, and which can comprise the samecompositions discussed previously for sidewall spacers 53.

The cross-sectional view of the construction of FIG. 10 has thesource/drain regions 57 and 67 entirely above bulbous region 30, andspaced from bulbous region 30 by gaps 70 between the source/drainregions and the bulbous region. In some aspects of the invention, it canbe advantageous to form isolation structure 40 with the bulbous regionmore shallow than that of FIG. 10 so that source/drain regions ofadjacent transistor devices extend to the bulbous region. For instance,FIG. 11 shows a structure similar to FIG. 10, but with the source/drainregions of transistor devices 50 and 60 extending to bulbous region 30of the isolation structure. The structures of FIG. 11 are labeledidentically to the structures of FIG. 10.

It can be advantageous to form the source/drain regions of adjacenttransistor devices to extend down to the bulbous region 30 of isolationstructure 40 to remove a source of junction leakage. Alternatively, itcan be advantageous to form structures of the type shown in FIG. 10where the source/drain regions are well above the bulbous region 30 ofisolation structure 40 so that the bulbous region does not impactperformance of adjacent transistor devices other than providing betterelectrical isolation between the devices than can be achieved with priorart isolation regions.

Although the isolation regions of FIGS. 10 and 11 have the stem 34extending upwardly above an uppermost surface of substrate 12, it is tobe understood that the invention encompasses other aspects (not shown)in which the stem is further polished after removal of layers 14 and 16(FIG. 8) so that the stem has an uppermost surface which isapproximately coplanar with an uppermost surface of substrate 12.

The aspect of the invention discussed above with reference to FIG. 5pertained to an embodiment of the invention in which an isotropic etchwas conducted immediately after removing the liner from along a bottomportion of the opening 18 of FIG. 4. Another aspect of the inventioncomprises a first anisotropic etch through the unlined portion of theopening followed by the isotropic etch. Utilization of the firstanisotropic etch can enable the corners adjacent the bulbous region(such as, for example, the corners 32 shown in FIG. 5) to havecontrolled sharpness. The aspect of utilizing the anisotropicetch/isotropic etch combination to control corner sharpness is describedwith reference to FIGS. 12 and 13.

Referring initially to FIG. 12, construction 10 is shown at a processingstage subsequent to that of FIG. 4. Identical numbering is utilized indescribing FIG. 12 as was used above in describing the embodiment ofFIG. 4. Thus, the construction 10 is shown to comprise the layers 16 and14 over substrate 12, and is shown to have the opening 18 extending intosubstrate 12. The processing stage of FIG. 12 has opening 18 extended toa greater depth than the opening is at the processing stage of FIG. 4due to utilization of an anisotropic etch to extend the opening throughthe unlined portion of FIG. 4.

Referring to FIG. 13, an isotropic etch is subsequently utilized to formthe bowl region 30 of opening 18. The aspect of FIG. 13 has smoothercorners 32 where the bowl region meets the stem region 34 than did theaspect of FIG. 5. In some applications of the invention, NF₃ and HBr areutilized for the isotropic etching of FIG. 13 as well as for theanisotropic etching of FIG. 12, and the amount of downward direction ofthe etch relative to sideward direction of the etch is controlled by theratio of NF₃ to HBr. An isotropic etch will typically etch about 70%downward relative to the amount that it etches laterally, and an etchwhich does greater than 70% downward relative to the amount that itetches laterally is typically considered to be an anisotropic etch.

The smoothness of the transition between the bulbous region 30 and thestem region 34 of opening 18 of FIG. 13 can improve characteristics ofan isolation structure formed within the opening relative to theembodiment of FIG. 5. In some aspects, the transition between the stemregion and widened region 30 can be smoothed by thermal oxidationutilized during formation of insulative material within opening 18 inaddition to, or alternatively to, utilization of the anisotropic etchthrough the unlined portion prior to the isotropic etch.

The various aspects to the invention discussed above with reference toFIGS. 1-13 can be utilized for numerous applications. In someapplications, the invention can be utilized for forming new trenchedisolation structures (for example, shallow trenched isolationstructures) for improving cell-to-cell isolation in memory arrays (forexample, dynamic random access memory arrays). The inventionincorporates a relatively minor change in standard trench isolationprocesses, and accordingly can be economically incorporated intoconventional processes. By adjusting the isolation region depth, and byadjusting the size of the bowl formed at the bottom of the isolationregion, cell side junction leakage can be reduced by shutting down partof a junction leakage path, which can help data retention. Thestructures of the present invention can be applicable for current andfuture DRAM generations, and can be incorporated into processing withoutadding new masks or complicated new processing levels.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1-26. (canceled) 27: A semiconductor construction, comprising: asemiconductor material; and an electrically insulative materialstructure extending into the semiconductor material, the structurehaving a bulbous bottom region and a stem region extending upwardly fromthe bottom region to a surface of the semiconductor material. 28: Theconstruction of claim 27 wherein the semiconductor material comprisessilicon. 29: The construction of claim 27 wherein the semiconductormaterial consists essentially of silicon. 30: The construction of claim29 wherein the insulative material consists essentially of silicondioxide. 31: The construction of claim 27 further comprising: a firsttransistor device on one side of the electrically insulative structure,the first transistor device having a pair of first source/drain regionsextending into the semiconductor material; a second transistor device onan opposing side of the electrically insulative structure from the firsttransistor device, the second transistor device having a pair of secondsource/drain regions extending into the semiconductor material; and theinsulative material providing electrical isolation between the first andsecond transistor devices. 32: The construction of claim 31 wherein oneof the first source/drain regions extends to the bulbous bottom region.33: The construction of claim 32 wherein one of the second source/drainregions extends to the bulbous bottom region. 34: The construction ofclaim 31 wherein the first and second source/drain regions are entirelyabove the bulbous bottom region.